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Ostracod taxonomy, morphometry, and separation
In order to attain the high temporal resolution for the selection periods and a reasonably resolved overview of d18OP for all sites, about 5000 sediment samples (1000 from each new site, 500 samples for both Ammersee and Lac d'Annecy) have to be processed. The well tested protocol includes desegregation, wet sieving, and drying with the aim to concentrate well preserved and clean ostracod valves without alteration of the isotopic composition of valve calcite by dissolution or deposition of calcite from the used agents. Subsamples of different taxa for isotope measurements have then to be selected, labeled and stored for transport. Those high sample numbers can only be processed in due time (i.e. with sufficient advance with respect to the isotope analyses and interpretation of the results) if at least three laboratories with adequate equipment, taxonomic experience, and technical staff are involved. Samples from the existing cores from Ammersee and Lac d'Annecy will be treated by the co-ordinator at LSCE-France, the samples from the new sites by LIÖAW-Austria (Mondsee and Jezioro Hańcza) and UAM-Spain (Lago d'Idro and Lago d'Iseo).
In addition to the indispensable sample treatment capacity, both the Austrian and Spanish partners will significantly contribute to the project by largely increasing the overall experience in freshwater ostracod taxonomy and by quantifying and interpreting changes in the ostracod faunal assemblages. Both groups are closely collaborating in the development of new methods to measure and describe subtle changes in the ostracod valve outlines. Within the project those methods will be exploited to refine the taxonomical separation of juvenile instars of Candonids (which due to the very small sample sizes will represent the majority of the samples selected for the isotope measurements) and to eventually add evidence for subtle changes in the physical and/or chemical conditions in the hypolimnion of the lakes.
